This invention relates to isopropoxy-, phenoxy- and halophenoxy- hydroxymethylphenoxycyclotriphosphazenes and to a process for producing same.
It is well known that the presence of phosphorus in polymeric materials imparts flame retardant properties to these materials. Flame retardancy is further enhanced by the synergistic effect of the combined presence of nitrogen and phosphorus, as provided by phosphazenes, for example. It is well recognized by those skilled in this art and should be clearly understood by others, however, that all known organic polymers will burn when subjected to a sufficiently intense heat source, whether or not they contain a fire retardant additive.
One disadvantage of using common flame retardants is that they contain significant amounts of chlorine and/or bromine which are evolved as gaseous hydrogen chloride and hydrogen bromide under fire conditions. Such evolution is undesirable in case of fires in closed areas in which people are present. Another drawback to these and other flame retardants is that they are generally present in the formulated polymeric material as an additive. Since they are not bonded to the polymer, they have a tendency, over a period of time, to leach out of the material, thus decreasing their effectiveness and causing possible toxicity hazards.
The use of hydroxymethylphenoxycyclotriphosphazenes as flame retardants in a polymeric formulation avoids both the problem of hydrogen chloride and hydrogen bromide generation and the problem of flame retardant leaching. The former problem is diminished as the hydroxymethylphenoxycyclotriphosphazene can be selected to contain little or no chlorine or bromine while the latter problem is greatly reduced as the hydroxymethylphenoxycyclotriphosphazene copolymerizes, via its hydroxymethylphenoxy functional groups, with the polymeric material.
Due to the value of such hydroxymethylphenoxycyclotriphosphazenes, it is desirable that an efficient, simple process be made available for their manufacture.
It is therefore an object of this invention to provide isopropoxy- and phenoxy- hydroxymethylphenoxycyclotriphosphazenes and a process for producing same.